Dial indicators

ABSTRACT

Low-friction dial indicators are provided wherein the linear motion of an indicator rod is converted to the rotary motion of the indicator needle by means of a flexible band wrapped about a cluster of rollers and connected to g guide way in which the rollers move substantially free of friction. Means are provided for pre-loading the rollers, for adjusting the sensitivity of the indicators and for providing multiple output from a single drive system.

[22] Filed:

United States Patent Paul [54] DIAL INDICATORS [72] Inventor: Igor L. Paul, West Peabody, Mass.

[73] Assignee: B. C. Ames Company, Waltham,

Mass.

March 24, 1969 [21] Appl. No; 809,552

[52] US. Cl. ..33/172 R, 116/129 R, 74/8922 [51] Int. Cl. ..G0lb 3/22 [58] Field of Search.33/l78 A, 172 A, 172 B, 169 A,

[ Oct. 17, 1972 OTHER PUBLICATIONS Rolamite: A New Mechanical Design Concept, Report No. SC-RR67- 656A, DF Wilkes, Sandia Laboratory, Albuquerque, N. M. December 1967. pp. 1, 54, 190, 191, 80, 82 199, 200, 201- 202, 207, 208,209,210- Group Art Unit 336.

Primary Examiner-Leonard Forman Assistant Examiner-Dennis A. Dearing Attorney-Morse, Altman & Oates [57] ABSTRACT Low-friction dial indicators are provided wherein the linear motion of an indicator rod is converted to the rotary motion of the indicator needle by means of a flexible band wrapped about a cluster of rollers and connected to g guide way in which the rollers move substantially free of friction. Means are provided for pre-loading the rollers, for adjusting the sensitivity of the indicators and for providing multiple output from a single drive system.

4 Claims, 20 Drawing Figures PATENTEnnm 17 I972 3.699 .473

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SHEET & [1F 4 INVENTOR. IGOR L. PAUL ATTORNEYS 1 DIAL INDICATORS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to dial indicators and more particularly is directed towards the actuating mechanism for dial indicators whereby linear motion is converted to rotary motion in a highly efficient manner.

2. History of the Prior Art Conventional dial indicators typically include a stem or rod which is reciprocated axially when a measurement is made. The rod customarily is provided with a rack in mesh with a pinion and through a gear train actuates the needle indicator on the dial. Such indicators, while reliable, are somewhat expensive to manufacture by reason of the need to manufacture the usually small gears with great precision so as to minimize play between the parts without binding. Also the gears are subject to wear after a period of long use, thereby reducing the accuracy of the instrument. Also, by reason of the rather extended gear train common to most dial indicators, a considerable amount of friction is involved in the operation of the indicator so as to necessitate a rather heavy pressure on the actuating stem to drive the indicator.

Accordingly, it is an object of the present invention to provide improvements in dial indicators and more particularly to provide a new and improved actuating mechanism for dial indicators. Another object of this invention is to provide a dial indicator having a simplified actuating mechanismwith a minimum number of parts yet one which is highly sensitive and is substantially friction-free in operation.

SUMMARY OF THE INVENTION This invention features a dial indicator comprising a rod adapted to be reciprocated longitudinally in response to an axial force,.a guideway having a pair of generally parallel surfaces connected to the stern, a cluster of rollers mounted in the guideway for movement therein and a flexible band wrapped about the rollers and connected to the guideway. At least one of the rollers is drivingly connected to a rotary indicator needle whereby the reciprocation of the stem will cause substantially friction-free rotation of the rollers and the indicator to provide an angular output representing measurement. Means are provided for adjusting the sensitivity of the instrument, for providing multiple outputs, for pre-loading the rollers, band and. guideway, for compound drive systems and for other flexible band-driven actuators.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view in rear elevation of a dial indicator made according to the invention,

FIG. 2 is an exploded perspective view of the FIG. 1 indicator,

FIG. 3 is a cross-sectional view taken along the lines 3-3 ofFIG. l,

FIG. 4 is a view in side elevation of a guideway, rollers and band assembly adapted to be pre-loaded,

FIG. 5 is a view similar to FIG. 4 but showing a modification thereof, A I

FIG. 6 is an exploded view in perspective showing a modification of the dial indicator of FIG. 1,

FIG. 7 is a view in front elevation of the FIG. 6 mechanism,

FIG. 8 is a view in front elevation, partly in section, showing a further modification of "the invention,

FIG. 9 is an exploded view perspective showing a further modification of the invention,

FIG. 10 is an exploded view in perspective showing another modification of the invention,

FIG. 11 is a view in front elevation, partly in section, of the FIG. 10 device,

FIG. 12 is a view in side elevation, partly in section, of the FIG. 1] device,

FIG. 13 and 14 are detailed views illustrating various drive arrangements,

FIG. 15 is a view in side elevation showing a compensated drive arrangement,

FIG. 16 is a view similar to FIG. 15 showing an adjustable compensation arrangement,

FIG. 17 is a view similar to FIG. 11 but showing a modification thereof,

FIG. 18 is a view in side elevation showing a further modification of the invention,

FIG. 19 is a sectional view in side elevation showing a dial indicator having a perpendicular input, and,

FIG. 20 is an exploded perspective view of the FIG. 19 instrument.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and to FIGS. 1, 2 and 3 in particular, there is shown a dial indicator 10 comprised of a generally circular housing 12 and an axially movable stem 14 passing diametrically through the housing and adapted to cause rotation of an indicator needle 16 about a dial face 18. The indicator needle 16 is mounted for rotation about an axis passing through the center of the dial and also passing perpendicularly through the longitudinal axis of the stem 14.

Actuating mechanism for converting the linear movement of the stem to the rotary movement of the needle is comprised of clustered rollers 20 and 22 parallel with the needle axis and in wrapped engagement in an S configuration with a flexible band 24. The band and rollers are mounted in a U-shaped frame 26 mounted to the side of the stem 14 opposite a cutaway portion 28 to define an elongated guideway 31 for the rollers and band. Preferably the frame 26 is mounted in a spring-loaded fashion against the stem by means of bolts 30 and springs 32 which serve to pre-load the assembly of the band and rollers.

The rollers 20 and 22 may be of the same diameter but in order to obtain amplification of the movement and thereby increase sensitivity it is preferred that they be of different size. In practice, the small roller is connected to the indicator needle 16 so that the two rotate together. The larger roller 20 preferably is provided with a stub shaft 34 which is mounted in a transverse slot 36 formed in the back wall of the housing 12. The opposite end of the shaft 34 is also mounted in a transverse slot formed in the face plate or the like. The band 24 is wrapped in an S-shaped configuration about the rollers in the manner shown with the upper end of the band secured against the inner flat face of the frame member 26 while the lower or right-hand end of the band is secured to the opposite flat face of the cutaway portion of the stem. It will be noted that the arrangement is such that the smaller roller 22 has its axis along the center line of the stem although perpendicular thereto to provide a geometrically uniform and centered configuration.

In practice, when the stem is reciprocated in response to a measurement being made it will move upwardly as viewed in FIGS. 1 and 2, this causing movement of the guideway and the band which is fixed thereto. As these components move, the rollers, which are held against displacement, will rotate by reason of the band undergoing longitudinal motion along the S- shaped path. Assuming proper tension on the hand, there will be no slippage between the band and the rollers and the movement will be substantially frictionfree. In order to prevent rotation of the stern about its longitudinal axis, the stem may be made non-circular as by providing a flat face 38 along those portions where it passes through the housing. Other means may be provided to prevent this rotation.

In the illustrated instrument the needle rovolutions per linear input displacementbf the stem are dependent only upon the diameter of roller 22 by 0, S D (where 0, is the needle angle in radians, S input displacement of the stem in inches, and D, is the diameter of the roller 22 in inches). Since the material stress limitations on the band 24 limit the diameter of the smaller roller 22 to something on the order of 0.030 inches 0.050 inches the maximum sensitivity would be on the order of 0.1 per full revolution of the indicator needle.

A natural return force is present in the system and this indicator return force can be provided by a variable width band and/or a variable thickness band (see FIG. and/or a return spring. In the second case the input frame must have non-parallel guide surfaces to provide constant sensitivity over the input stroke.

The sensitivity of the instrument can be controlled over a small range by adjusting the guide surfaces to be non-parallel as, for example, is illustrated in FIG. 16.

In FIG. 15, the guideway frame is represented by reference character 26' with rollers and 22' in wrapped engagement with a flexible band 24' the thickness of which tapers lengthwise. In order to maintain parallel rolling surfaces the opposing faces of the frame 26 are not parallel thus compensating for the tapered thickness of the band 24'.

In FIG. 16 a guideway is formed by a frame 40 corresponding to the frame 26 and stem portion 14 of FIG. I. Rollers 42 and 44 wrapped in a band 46 are mounted in the guideway. The guideway frame is generally rectangular being formed with a fixed U-shaped portion and a movable segment 48 providing one of the guideway surfaces. The segment 48 is hinged to the fixed portion of the frame as by a flexure hinge joint 50, or the like, which permits limited angular movement of the segment 48. The free end of the segment 48 is movable to and away from the fixed portion of the frame as by means of an adjusting screw 52. Manipulation of the screw 52 serves to change the angular relationship between the guideway surfaces which permits adjusting the sensitivity of the device over a small range. It will be understood that by changing the angle of the segment 48 the rotation of the rollers will be altered to a limited extent. It will be understood that the distance the frame 40 has to move for the smaller roller 44 to make one revolution will increase as the angle of the segment 48 is increased from a parallel position with surface 46.

In order for the actuating mechanism to function properly, it is necessary that the band and rollers be assembled in such a way that sufficient tension is placed on the band so that there will be no slippage between the rollers and the band. In order to assemble the components quickly and easily under the proper tension pre-loading arrangements are provided and illustrated in FIGS. 4 and 5. In FIG. 4 rollers 54 and 56 are wrapped by a band 58 and mounted in a guideway comprised of a U-shaped frame 60 and a movable-plate 62. Spring-loaded screws 64 and 66 are provided for clamping the plate 62 under tension down against the frame 60 and the roller cluster. The band 58 has one end fixed to the bottom portion of the frame and its opposite end connected to the upperleft-hand leg as viewed in FIG. 4. By tightening the screws 64 and 66 the plate 62 will move down towards the frame, placing tension on the band 58. The screws are tightened until the desired band tension is achieved. The springs between the screws and the plate 62 will serve to maintain the tension in a resilient fashion.

In the FIG. 5 embodiment, a cluster of rollers 68 and 70 engages a band 72 mounted in a guideway formed by a U-shaped frame 74 and a plate 76. The upper ends of the leg of the U-shaped frame 74 are cut on the bias at 78 to receive a wedge-shaped member 80. An adjusting screw 82 passes through the plate 76 and each member and threads to the leg of the frame. The plate 76 and each wedge-shaped member are formed with enlarged openings 84 and 85 to accommodate the shank of the screw and permit lateral displacement. The band 72 is attached at one end to the lower face of the frame member 74 and the upper end is connected either to the plate 76 or to the right-hand wedgeshaped member 80 as viewed in FIG. 5. Pre-loading of the band is achieved by tightening the screws 82, this causing a displacement to the right of the plate and/or the wedge thereby causing the band to tighten.

Referring now to FIGS. 6 and 7 of the drawings there is disclosed a modification of the dial indicator and in this embodiment a compound actuating mechanism having multiple outputs is provided. The mechanism comprises a stem 86 to which is mounted a frame 88 defining a guideway 90 for a cluster of rollers 92 and 94 wrapped in a band 96. The smaller roller 92 is drivingly connected to the larger of a second cluster of rollers which includes rollers 98 and 100. The latter two rollers are connected by a common band 102 causing the rollers to rotate in unison whenever the roller 92 is rotated. In order to maintain tension on the band 102 rollers 104 and 106 are provided. These rollers are connected by means of at least one common band 108 looped over the two rollers in a figure 8 fashion offset from the band 102. The roller serves as the primary output and is provided with an indicator needle 110 the axis of which intersects perpendicularly the longitudinal axis of the stem 86. Another indicator needle 112 is connected to the roller 98 to provide a secondary output. It will be understood that reciprocation of the stem 86 will cause displacement of the frame 88, this in turn rotating the roller 92 and thereby the rollers 98 and 100. The arrangement provides greater sensitivity of the input motion.

Referring now to FIG. 8 there is shown a further modification of the invention and in this embodiment a cluster of four rollers 114, 116, 118 and 120 are connected by bands 122 and 124. The bands are looped over pairs of rollers in paths forming intersecting figure 8 configurations with band 122 connecting rollers 114 and 116 and band 124 connecting rollers 118 and 120 in a manner similar to the left-hand cluster of FIG. 6. Roller 120 is provided with a large indicator needle 126 as the primary output while roller 116 is provided with a smaller indicator needle 128 as the secondary output. The roller cluster is driven by means of a stern 130 to which is attached a band 132 wrapped about a stub shaft 134 for the roller 122. Preferably, the stub shaft is mounted in a bushing or jewel bearing. Reciprocation of the stem 130 will cause the band 132 to unwind from the stub shaft 134 to which it is affixed, this causing the stub shaft to rotate thus driving the roller cluster. A return force for the stem may be provided by selection of the configuration of the band 132 or by means of an auxiliary spring connecting the stem to the housing.

Referring now to FIG. 9 there is shown further modification of the invention and in this embodiment a compound roller cluster is employed. The mechanism includes a stern 136 connected to an open rectangular frame 138 forming a guideway for a cluster of rollers 140 and 142 wrapped by a band 144. Roller 140 is drivingly connected to a roller 146 in a second cluster of rollers which includes a roller 148 both wrapped by a band 150. The second roller cluster band is mounted in open frame 152 forming a guideway for the second cluster. Roller 148 is provided with an indicator needle 154 to provide the output. It will be understood that reciprocation of the stem 136 will cause linear reciprocation of the frame 138 accompanied by rotation of the first roller cluster. Rotation of the first roller cluster will simultaneously cause rotation of the second roller cluster this, in turn, causing linear reciprocation of the frame 152 and rotation of the indicator needle 154. In order to prevent rotation of the frame 152 a channel comprised of fixed guide elements 156 and 158 is provided on opposite sides of the movable frame 152.

Referring now to FIG. there is shown another modification of the invention and in this embodiment a stern 160 is connected to a shaft 162 by means of a band 164 fastened to a boss 166 on the stem and wrapped about the shaft. The shaft 162 drives a roller cluster which also includes rollers 168 and 170, both rollers being wrapped by means of a band 172 and mounted in a guideway frame 174. An indicator needle 176 is connected to the smaller roller 170 to provide the output. The guide frame 174 is displaced when the stem 160 is moved and is mounted in a guide channel formed by a frame 178. In order to adjust to the sensitivity of the mechanism the frame 178 is pivotally mounted about an axis perpendicular to the stem 160 and a screw adjust device 180 is provided for imparting a selected angular tilt to the frame 178. It will be un derstood that as the stern 160 is moved axially the band 164 will unwrap from the shaft 162 causing the shaft to rotate, this in turn rotating the indicator needle 176 and displacing the guide frame 174 within the channel of the frame 178. The adjustment of the frame 178 may also be employed in the FIG. 9 embodiment. A return spring may be included.

FIGS. 11 and12 show an instrument similar to the FIG. 10 embodiment but without the angularly adjustable channel for the guideway frame. It will be noted in FIG. 11 that the indicator needle output roller is centered with respect to the dial and intersects perpendicularly with the longitudinal axis of the stem to provide a symmetrical instrument.

The tape drive such as employed in the embodiment of FIGS. 8, 10, 11 and 12 may be applied as an input from any direction in the mechanic s plane as suggested in FIGS. 13 and 14. In these latter figures a tape 132 is wrapped about a stub shaft 134'. In FIG. 13 the tape is wrapped once about the stub shaft and the input is in the direction of the arrow. In the FIG. .14 arrangement the tape is wrapped several times about the stub shaft and the input may be applied in either the full line or dotted line direction. In the FIG. 14 arrangement the varying of the effective shaft radius caused by the over lapping of the band about the stub shaft will introduce a small error in the output which may be compensated for by varying the angle of the guide frame as suggested in FIG. 15. Another method of compensation would be by changing the point of connection between the stub shaft and the stem. For example. in FIGS. 10 and 11, the band is connected to the end of a boss and extends generally parallel to the stem with the stub shaft displaced slightly from the stem. By moving the point of connection with the stem closer to the stem body, the band will unwrap at an angle rather than parallel to the stem thereby effectively changing the rate of rotation of the stub shaft with respect to the movement of the band.

Referring now to FIG. 17 there is disclosed a dial indicator which is a modification of the FIG. 11 device. In this embodiment a guideway frame 182 is reciprocated by means of a cluster of rollers 184 and 186, the rollers in turn being driven by means of a band 188 attached to the frame 182 and wrapped about the rollers. The larger roller 184 is provided with a stub shaft 190 which is wound about by means of another band 192, one end of which is attached to a boss 194 extending from the side of a stern 196. In addition to a primary output provided by an indicator needle 198 which rotates upon displacement of the stem 196, a secondary output is provided by a pointer200 attached to the guideway frame 182 and extending out to the front of the dial face for linear movement along a scale 202 appearing on the dial face.

Referring now to FIG. 18 there is disclosed a further modification of the invention and in this embodiment a cluster of rollers 204 and 206 is mounted in the guideway of a frame 208 and wrapped about by means of a band 210. The roller 206 drives a larger roller 212 provided with scale markings 2114 registering with a scale 216 tangential thereto. A linear input motion to the roller 204 will cause the dial. roller 212 to rotate and translate at a preselected ratio.

Referring now to FIGS. 19 and 20 there is illustrated a right angle indicator in which the input is provided by a stern 218 perpendicular to and preferably coaxial with the axis of an indicator needle 220 or at right angles to a dial face 222. The indicator includes a housing 224 having a hollow hub portion 226 in which the stem 218 is mounted for reciprocation. The main body of the housing supports a guideway frame 228 supporting a cluster of rollers 230 T232 engaged by a flexible band 234 wrapped about the rollers in an S configuration. The guideway frame 228 is slidably mounted to the housing 224 by means of a pair of rods 236 and 238 extending from opposite ends of the frame out through the walls of the housing. Roller 232 is connected to the indicator needle 220 to provide the dial output. Connected between the stem 218 and the guideway frame 228 is a flexible band 240 looped over a pair of rollers 242 and 244. The roller 242 is mounted in the housing tangentially to the stem 218 while the roller 244 is mounted in the housing tangential to the lower face of the guideway frame 228 directly above the roller 242.

The band 240 is attached to the upper end of the stem 218 and passes downwardly around the roller 242, up-

wardly over the roller 244, and then at right angles engages one end of the guideway frame in the manner shown in FIGS. 19 and 20. With this configuration axial displacement of the stern 218 will cause a right angular displacement of the guideway frame 228, this in turn causing the roller cluster to be rotated and move the indicator needle 220. It might also be noted that the rods 236 and 238 may be employed at secondary points of input insofar as their axial displacement will cause rotation of the indicator needle.

While various embodiments of the invention have been illustrated it will be understood that the features of some embodiments may be combined in various ways with other embodiments. Also, various modifications may be made such as the use of a wire of circular cross-section in place of a band for engaging the rollers.

Having thus described the invention what I claim and desire to obtain by Letters Patent of the United States 1. A dial indicator comprising a. a housing having a generally circular dial,

b. a stem mounted for axial displacement to said housing and extending diametrically of said dial,

is. a recess in said stern extending along one side thereof of a depth greater than one-half the thickness of said stem, the bottom of said recess being parallel to the longitudinal axis of said stem,

d. a frame mounted to said stem and together therewith defining a pair of substantially parallel oppositely facing spaced surfaces one of which constitutes the bottom of the recess in said stem,

e. at least two mutually parallel rollers disposed between said surfaces with one of said rollers extending within said recess in said stem and with the axis of said one roller intersecting the longitudinal of said band and rotation of said rollers and said needle. 2. A dial indicator according to claim 1 wherein said frame includes a movable wall for adjusting said surfaces relative to one another.

3. A dial indicator according to claim 2 including a pair of spring-loaded screws threaded to said frame and passing through said wall for resiliently mounting said wall to said frame.

4. A dial indicator comprising a. a housing having a substantially circular dial mounted therein,

b. a stern mounted for axial displacement to said housing diametrically of said dial, means defining a recess in said stem the depth of which is greater than one-half of the thickness of said stem, the bottom of said recess being parallel to the longitudinal axis of said stern,

c. frame means carried by said stem including at least one wall portion oppositely facing and parallel with the bottom of said recess in said stem,

. a plurality of mutually parallel rollers at least two of which are of different diameters disposed between said parallel portions of said frame and said stem with one of said rollers extending within said recess in said stem and with the axis of said one roller intersecting the longitudinal axis of said stem and co-planar therewith, I

e. an indicator needle connected to said roller within said recess in said stem and movable therewith with respect to said circular dial,

f. at least one flexible band entrained about the adjacent rollers in a generally S-shaped fashion,

g. means connecting opposite ends of said band to said stem and said frame respectively, whereby axial displacement of said stem will cause rotation of said roller and said indicator needle,

. said needle being co-axial with the said one roller to which it is connected.

IF IF 

1. A dial indicator comprising a. a housing having a generally circular dial, b. a stem mounted for axial displacement to said housing and extending diametrically of said dial, c. a recess in said stem extending along one side thereof of a depth greater than one-half the thickness of said stem, the bottom of said recess being parallel to the longitudinal axis of said stem, d. a frame mounted to said stem and together therewith defining a pair of substantially parallel oppositely facing spaced surfaces one of which constitutes the bottom of the recess in said stem, e. at least two mutually parallel rollers disposed between said surfaces with one of said rollers extending within said receSs in said stem and with the axis of said one roller intersecting the longitudinal axis of said stem and co-planar therewith, said rollers having a combined cross sectional dimension greater than the spacing between said surfaces, f. a flexible band attached by its ends to an opposite end of each of said surfaces and wrapped in reversing directions about adjacent rollers, g. an indicator needle rotatably mounted to said housing about an axis co-planar with the axis of said stem and drivingly connected to said one roller, h. axial displacement of said stem causing movement of said band and rotation of said rollers and said needle.
 2. A dial indicator according to claim 1 wherein said frame includes a movable wall for adjusting said surfaces relative to one another.
 3. A dial indicator according to claim 2 including a pair of spring-loaded screws threaded to said frame and passing through said wall for resiliently mounting said wall to said frame.
 4. A dial indicator comprising a. a housing having a substantially circular dial mounted therein, b. a stem mounted for axial displacement to said housing diametrically of said dial, means defining a recess in said stem the depth of which is greater than one-half of the thickness of said stem, the bottom of said recess being parallel to the longitudinal axis of said stem, c. frame means carried by said stem including at least one wall portion oppositely facing and parallel with the bottom of said recess in said stem, d. a plurality of mutually parallel rollers at least two of which are of different diameters disposed between said parallel portions of said frame and said stem with one of said rollers extending within said recess in said stem and with the axis of said one roller intersecting the longitudinal axis of said stem and co-planar therewith, e. an indicator needle connected to said roller within said recess in said stem and movable therewith with respect to said circular dial, f. at least one flexible band entrained about the adjacent rollers in a generally S-shaped fashion, g. means connecting opposite ends of said band to said stem and said frame respectively, whereby axial displacement of said stem will cause rotation of said roller and said indicator needle, h. said needle being co-axial with the said one roller to which it is connected. 